(CNN) – Voters in Maine will decide next week whether to overturn the legislation signed by Gov. John Baldacci nearly six months ago that allows same-sex couples to wed.

Baldacci, who originally opposed the legislation, said upholding the bill comes down to a fundamental understanding of equal protection and constitutional responsibility.

"Initially, I had the opinion for several years that civil unions were the limitations of what I was willing to support," Baldacci said. "But, the research that I did uncovered that a civil union didn't equal a civil marriage."